Intercell-Interference in the Gaussian MISO Broadcast Channel

Intercell interference (ICI) is the substantial difference between a cellular and a non-cellular communication system. Effective modeling of the cellular downlink as a Gaussian broadcast channel requires that the ICI powers at the user positions are known to the basestation (BS), as it otherwise, cannot attempt to approach (or even know) its capacity region. However, ICI depends on the transmit processing of the BSs in the neighboring cells, which furthermore is subject to change quickly due to temporal scheduling. The BS therefore only has limited knowledge about the true ICI powers. In this paper, the implications of this lack of knowledge about ICI power on the achievable sum- rate of a Gaussian MISO (multi-input, single-output) broadcast channel is examined. Four different approaches on dealing with unpredictable ICI are discussed and their performance compared to the single-cell (or non-cellular) Gaussian broadcast channel.